Loc: close to the inner rim of the Orion Spur, about halfway along its length.

Posted 12 November 2012 - 11:59 AM

I use to do it the same way I would align my finder scope. I had the smaller scope in a set of adjustable tube rings. Align the mount to the main/larger scope and then align the smaller scope to the main scope with the tube ring screws. The only pitfalls I had was the hassle of the extra time in setting up, balancing, etc. and if the ring screws weren't tight enough the scope would have a tendency to slide inside the rings. Plus, on a GEM one scope would inevitably end up in a less than ideal position for observing. I'm visual only. I hope this helps

Those side-by-side mounts are a bit of a marketing-man's wet-dream. They really don't work for visual; they are really designed for wide-field AP.

EXCEPT with Ken Dauzat's saddle, which allows the second 'scope to be accurately aligned with the first 'scope. I am able to get my 2 'scopes within seconds of each other, which makes A-B comparisons of planets at high mags a dream.

I set up both 'scopes in the saddle in my workshop, get them balanced, and then carry it out to the GEM. This is very awkward, and if I have long 'fracs mounted, the GEM head is above my head so it is quite a lift.

The other downside is that Ken is no longer in business, and his saddles are NLA.

If one of the scopes is small enough then 3 point rings work very well. If you have larger scopes or need to swap scopes around then you need to look at the saddles themselves.

Up and down (tilt) can be adjusted using metal shims under the saddle mounting bolts. The shims should be very thin (think thick foil). Yes it's a bit time consuming but you end up with saddles that are well aligned. There is often enough play in the saddle mounting bolts to adjust for small amounts of side to side movement.

There are also a number of commercial adjustable saddles. ADM and APM both have saddles with addition tilt and side to side adjustments.

Using shims gets you saddles that are very close to alignment but it takes some work and if you use a variety of scopes with your side by side configuration you may find that the alignments of their dovetail bars may not be consistent.

The commercial adjustable saddles give you more flexibility and speed of adjustment but they add substantial weight and height and extra cost.

Once aligned the only real downsides to good solid side by side configurations are a) extra weight but this is often mitigated by moving the total mass closer to the mount compared to piggy back setups and b) balancing the scopes is more complex. It takes a bit longer to achieve balance in all directions.

A major downside for the simpler designs is the use of the Vixen dovetail. Really, D-series saddles should be the minimum configuration, as in the more expensive models.

Adjusting with shims is an example in masochism. You would never want to disassemble it. With Ken's design, interchanging is easy, needing a leisurely 15 minutes to get everything swapped in and aligned.